A number of touch fastening systems, such as those found in personal care and other products, feature arrays of discrete hooking structures that extend from a common base. Many such products are formed from resin, such as by molding the base and hooking structures from a unitary resin flow, or severing the rails of a plastic extrusion, or by molding the base with preform structures (e.g., straight stems) that are later deformed to create hooking structures. Some hooking structures are hook-shaped, with tips that extend in a primary lateral direction to define a crook. Some hooking structures have multiple crooks, with an example being a ‘palm tree’ structure with tips extending in two opposite directions. Some hooking structures are known as ‘mushroom-type’ and feature engaging heads that overhang the base all around a supporting stem.
Molding hooking structures with overhanging heads, and then removing such structures from their cavities without opening the cavities requires selecting a resin and a hook shape that will allow the molded elements to temporarily deform while being pulled from the mold, and that will also provide a desired level of peel resistance during use. How to design hook shapes to enable demolding from closed cavities is taught, for example, in U.S. Pat. No. 4,984,399 to Provost.
Improvements are continuously sought to facilitate the manufacture of fastener products with desired properties, including peel and shear strength and touch softness.